Here's the hypothetical:
Congress is adjourned, but the Example Caucus wants it to convene again as soon as possible. Congress plans to take recess for more than three days, so they've scheduled senator Bob to do a pro-forma session.
Ahead of the session, Senator Alice and Senator Abe of the Example Caucus quietly take their seats in the chamber. When Senator Bob asks for unanimous consent to convene, they are quiet. But when Senator Bob asks for unanimous consent to adjourn, they object!
Now check me on this next part:
The Senate is therefore not adjourned, is that not so? And since Alice and Abe have a 2-1 majority over Bob, it is pointless for Bob to call for a vote to adjourn. As Alice and Abe and Bob argue, the rest of the Example Caucus files into the chamber. Now the Senate is in session (a regularly scheduled session, in fact), and they have a quorum.
They can now conduct business, can they not?
I'm trying to find out if this would work, but I have no idea if it would. If I've based the hypothetical on false assumptions and this is all silly, I apologize. I meant no harm. I'm not well versed in law that's why I'm asking.